Wiping contact assembly for plugboard



March 14, 1961 c. sn-z 2,975,395

WIPING CONTACT ASSEMBLY FOR PLUGBOARD Filed Feb. 10, 1955 3 Sheets-Sheet1 *tINVENTOR.

Gil en. C. Sitz BY March 14, 1961 G. c. slTz 2,975,395

WIPING CONTACT ASSEMBLY FOR PLUGBOARD Filed Feb. 10, 1955 3 Sheets-Sheet2 IN V EN TOR.

March 14, 1961 G.c.s1Tz 2,975,395

WIPING CONTACT ASSEMBLY FOR PLUGBOARD Filed Feb. 10, 1955 3 Sheets-Sheet3 IN VEN TOR. Gilbert C. 5&2.

United States Patent WIPING CONTACT ASSEMBLY FOR PLUGBOARD Gilbert C.Sitz, Harrisburg, Pa., assiguor to AMP Incorporated, a corporation ofNew Jersey Filed Feb. 10, 1955, Ser. No. 437,323

12 Claims. 01. 339-252 This invention in general relates to plugboardassemblies for electrical accounting machines, computers, and the likeand more particularly to an electrical contact assembly which providescircuit connections between fixed and movable plugboards of a plugboardassembly. For purpose of illustration the invention will be set forth inthe present specification in association with plugboards and relatedparts such as are found in electrical accounting machines.

It has become the prevailing practice to provide in electricalaccounting machines of the perforated record controlled type a fixedpanel on which are arranged a multiplicity of electrical contacts inrows and columns, certain of the contacts being connected to the sensingelements or brushes 0f the machine and the remainder pro vidingterminals for the leads connected to the instrumentalities that performthe operative functions of the machine under control of perforatedrecords. A control panel cooperates with the fixed panel to providethrough the electrical contacts the desired circuit connection patternbetween the sensing elements and the instrumentalities to be operated inaccordance with the predetermined pattern. To this end the control panelis provided with removable plugs or pin contacts which are adapted toengage and couple the corresponding contacts on the fixed panel.Commonly, the control panel and its contacts are removable as a unitfrom the plugboard assembly, where by a separate control panel may befurnished for each arrangement desired.

Generally the control panel is carried by a frame which may be pivotablyconnected to the fixed panel, pivotal movement of the frame bringing thepanels into operative relationship. To distribute evenly the contactpressure throughout the assembly in order to prevent warping of thecontrol panel, it is preferred that the panels, or plugboards, first bebrought to a parallel position with the two sets of contacts being in anoverlapping equally spaced relationship. Subsequent movement of themovable or control panel along the fixed panel causes the contacts toengage simultaneously and effects even distribution of contact pressure.A mechanism for producing the movement of the panels, as described, isdisclosed in my copending application, Serial No. 411,969, filedFebruary 23, 1954, now Patent No. 2,927,295, dated March 1, 1960. Thepresent invention is here described in a form suitable for incorporationin the structure disclosed in my copending application but other formswill readily occur to others skilled in this and related arts.

To render such a plugboard assembly practical, good electrical contactbetween the panels must be assured. It has been found, however, thatmerely bringing the control panel plugs into engagement with the fixedpanel terminals may fail to give optimum performance due, among othercauses, to contact failure resulting from the accumulation thereon ofdust and films and by corrosion and pitting of the contact surfaces.

Accordingly, it is an object of the present invention to provide acontact assembly for plugboards which assures lit a clean and positiveelectrical contact between the contact elements.

Another object is to provide in a contact assembly for plugboards acontact member which eiTects an ultimate engagement with a matingcontact plug at a freshly wiped point on the plug.

A further object is to provide a contact assembly for plugboards whereinthe relative movement of the contact carriers is amplified as translatedinto wiping action between the contacts.

Still another object is to provide in a plugboard assembly aself-locking contact assembly tending to maintain the plugboards ininterconnected relationship.

A still further object of the present invention is to provide in aplugboard assembly a spring contact which is simple to insert and tolock in position in the associated contact carrier.

Still another object of the present invention is to provide in aplugboard assembly a spring contact of a durable single-piececonstruction.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich:

Figure l is a side view of a plugboard assembly partly broken away toillustrate the mounting of the contact assembly of the presentinvention;

Figure 2 is a partial front view in elevation of the plugboard assemblywith certain parts being broken away as indicated in Figure 3 from A toE to illustrate the details of mounting the contact assembly;

Figure 3 is a detailed fragmentary view of the plugboard assemblyillustrating the contact assembly in contacting relationship;

Figure 4 is a plan view of a spring contact for the fixed plugboard ofthe assembly;

Figure 5 is a side view of the spring contact shown in Figure 4;

Figure 6 is a plan view of the contact portion of the spring contactmember of Figures 4 and 5;

Figure 7 is an end view of the spring contact member of Figures 4 and 5illustrating the relationship of the contact portion to the springportion thereof;

Figure 8 is a diagrammatic view of the contact assembly illustrating themovement of the contact elements during operation of the plugboardassembly;

Figure 9 is a perspective view of another embodiment of the contactportion of the spring contact member;

."Figure 10 is a diagrammatic view illustrating the movement of. thecooperating plug contact and the contact portion illustrated in Figure9;

Figure 11 is a side view of a spring contact member including thecontact portion shown in Figure 9;

Figures 12 and 13 are perspective views of other embodiments of thecontact portion of the spring contact member;

Figure 14 is a diagrammatic view illustrating the movement of thecooperating plug contact with the contact portions shown in Figures 12and 13;

Figure 15 is a perspective view of another embodiment of the contactportion of the spring contact member;

Figure 16 is a diagrammatic view illustrating the relationship of thecooperating contact pin and the contact portion of Figure 15 during theconnective movement of the plugboard assembly; and

Figures 17 and 18 are perspective views of other embodiments of thecontact portion of the spring contact member.

Referring now to Figure 1, there is illustrated the plugboard assemblywhich includes a movable plugboard 1 shown loosely pivoted at 2 to afixed plugboard 3 adapted to be rigidly aflixed by bolts 4 to the frameof an elec-- ttical accounting machine or the like. A mechanism (notshown) of a type known in the art is provided to swing movable plugboard1 about pivot 2 from the open position as shown to a position parallelfixed plugboard 3 and then to lift or move plugboard 1 upwardly alongthe fixed plugboard by a pre-determined amount. Such means form no partof the present invention and hence are omitted for purposes of clarity,an example of a suitable mechanism being shown and described in myaforesaid patent.

Fixed plugboard 3 is provided, as shown in Figure 2, with a base panel 6having a plurality of apertures arranged in rows and columns which areadapted to receive and support in position a like number of contactelements 7, some of which are coupled to the sensing elements of themachine while others are coupled to the various instrumentalities thatperform the operative functions. conventionally, movable plugboard 1 isprovided with a removable panel 9 having a plurality of apertures 11,corresponding to apertures 5, in which contact plugs or pins 13 areadapted to be mounted, pins 13 being arranged to engage correspondingcontact elements 7, as shown in Figure 3, when the plugboard assembly ismoved to its closed or interconnected position. Apertures 5 on panel 6of the fixed plugboard arc intercepted by longitudinal grooves 15 for apurpose to be explained hereinafter.

Pin 13 is preferably in the form of a plug or jack and includes a barrel14 which is detachably secured to plugboard 1 within apertures 11 by anysuitable means known in the art. For example, a friction fit of barrel14 within apertures 11 will suflice, however, it is preferred that theplug be of the form shown and described in my copen-ding application,Serial No. 418,413, filed March 24, 1954, now Patent No. 2,903,670,dated September 8, 1959. A ferrule 16 integral with barrel 14 provides ameans for electrically and mechanically connecting lead 17 to the pin ofplug 13. The contact portion of pin 13 cooperates, in a mannerhereinafter described, with a corresponding contact member 7 to effectelectrical continuity between lead 17 and the lead 18 which isterminated in contact member 7, as in Figure 3.

As the movable plugboard is swung inwardly toward and to a positionparallel to the fixed board, contact pin 13 is initially disposed inoverlapping spaced relationship with respect to contact member 7. Uponfurther operation of the plugboard mechanism, the movable board isslidably moved along the fixed plugboard such that each pin 13 engagesthe corresponding contact member 7 to accomplish the desired electricalconnections. members 7 are contemplated to include spring means which,upon deflection by the moving contact pin 13, eventually produces apredetermined contact pressure between the elements. To this end eachcontact member 7 includes, as shown in Figures 4 through 7, a springportion 19 which characteristically is constrained to deflect in a planeperpendicular to the movement of the pin about a bending axis parallelto the movement of the pin. Typically a leaf spring will afford thecharacteristics desired in spring portion 19. With such an arrangement awiping action, to be described in detail, of the pin and of the contactsurface of member 7 may be had that enhances the electrical quality ofthe contact between the elements by removing or scraping away anyaccumulation of foreign matter which might interfere with the making ofa clean contact.

Generally designated at 20 in Figure 4 is the means by which contactmember 7 is mounted and retained within the apertures of the fixed boardin a manner such that the plane of spring portion 19 is maintainedsubstantially in the desired position parallel to the path of pinmovement. An indentation 21, struck up from a central portion at thebase of spring 19 leaving shoulders 25, provides the link integrallyconnecting mounting 20 with the remainder of the contact member.Shoulders are Contact adapted to fit within grooves 15 in abuttingrelationship with the face of the plugboard in order to maintain spring19 in a fixed plane on a face of the plugboard 3. Stabilizing theforward end of mounting means 20 within an aperture 11 is a generallycylindrical barrel portion 23 having a diameter closely approximatingthe aperture diameter. Protruding from the rearward face of plugboard 3is a semi-cylindrical portion 27 extending from the side edges of whichare wings 29. The forward edges of wings 29 facing the plugboard arecurved so that upon spreading wings 29 outwardly, such edges will engagethe plugboard in a camming action to draw shoulders 25 into tightengagement with the forward face of the plugboard, thus securelyanchoring contact member 7. Intermediate cylindrical portion 23 andextension 27 there is provided a tapering socket or receptacle 31adapted to receive a mating taper pin 33 which is affixed to theelectrical conductor or lead 18.

At the free end of spring 19 there is provided a contact portion or tab35 through which electrical contact is had with pin 13. In the form ofcontact member 7, shown in Figures 4 through 7, tab 35 is asubstantially fiat extension of spring 19 but with the plane thereof setat an angle with respect to the plane of spring 19 as best shown inFigure 7. The relationship of corresponding apertures 5 and 11 is suchthat, upon mounting contact member 7 on the fixed board, the leadingside of tab 35 adjacent the edge will be disposed in the path ofmovement of pin 13. A relatively narrow contact surface 37 is providedon tab 35 in the form of a head or rib facing the path of movement ofpin 13 as best shown in Figure 8, the specific form and character of thecontact surface to be described in detail hereinafter.

As thus arranged pin 13 will initially engage contact rib 37 near theleading side of tab 35, the relationship of the elements beingdiagrammatically illustrated by the dotted lines in Figure 8. As pin 13continues to move upwardly, it will ride along contact surface 37causing tab 35, under constraint of spring 19, to move perpendicularlyto the line of pin movement, as indicated by the arrow, ultimately toreach the final point of contact indicated by full lines in Figure 8.

It will be observed from Figure 8 that the path of pin movement and aline segment representing the motion of tab 35 are the legs of a righttriangle, the hypotenuse of which is a line segment representing theactual path of contact between the elements.

Accordingly, the upward movement of the pin as translated into wipingaction along the contact rib 37 is amplified since the pin wipes along acontact path greater in length than the distance it has traveled. Thisamplification augments the tendency of the wiping action to free rib 37of any accumulated foreign matter. With the tab 35 being set at an angleof to the plane of spring portion 19 the greatest amplification isattained and presents a large target area for the pin while not undulyincreasing the force required to deflect the spring.

To assure, however, good electrical contact with the pin, contact rib 37is arranged so that during the upward motion of the pin, a predeterminedlength of the pin is first wiped and then rewiped or recontacted with nthe wiped length to result in a final contact on the pm at a freshlywiped point. To this end a first portion 37a of rib 37 is inclineddownwardly toward the base of the contact member 7 and away from thedirection of movement of the pin and a second portion 37b is inclinedsubstantially opposite to the inclination of portion 37o, a rib 37 thushaving a generally V-shaped configuration with the apex of the Vpointing in a direction along the length and toward the base of thecontact member 7'. It should be apparent, however, that rib 37 issusceptible of taking a variety of forms to effect recontacting the pinwithin the prewiped length. Typically, the final point of contact on pin13 may be approximately midway of the prewiped path, in which case, theV-shape of rib 37 is formed by rib 37b having an inclination the same asportion 37a but of a length half as long, or alternatively, the legs ofthe V may be substantially of the same length but with portion 37b beinginclined at an angle half as great as portion 37a. In general, however,assuming that a line representing the direction of pin movement togetherwith another line substantially perpendicular thereto and representingthe direction of spring deflection define a plane, such lines beingshown as arrows in Figure 8, then inclination of rib 37 in such planewith re spect to the line of pin movement, as afforded by the angularset of contact portion 35, provides a cam-like arrangement fordeflection of spring 19. Inclination of rib portion 37a out of theaforesaid plane efiects the desired prewiping action, recontacting ofthe pin within its prewiper length being accomplished by fixing thefinal contact point on rib portion 37b equidistant from said plane withan intermediate point or rib portion 3711.

In operation, as the pin 7 first engages contact tab 35, as shown indotted lines in Figure 8, the contact point will fall near the leadingend of rib portion 37a. As the pin moves upwardly, the point of contactwill be shifted toward the nose of the pin in accordance with theinclination of rib 37 until the apex of the V is reached. Further upwardmovement of the pin causes the point of contact to retrace the prewipedpath in accordance with the inclination of rib portion 37b until thefinal point of contact is reached, near the rear side edge of thecontact tab 35, within the limits of the prewiped length of the pin.

In the embodiment of my invention shown in Figures 9 to 11, by impartinga ramp-like configuration to the contact rib, the camming action fordeflecting spring portion 19 may be obtained within the design of thecontact rib alone. Thus, as best shown in Figure 11, contact portion 39is substantially a flat coplanar extension of spring portion 41 withcontact rib 43 progressively increasing in elevation above the plane ofspring portion 41 from its forward point 43a to its terminal point 43b.With contact rib 43 having a generally V-shaped configuration, theoperation, as indicated in the action diagram, Figure 10, will besubstantially the same as has been described in connection with theembodiment of my invention shown in Figures 4 through 8. Accordingly,spring portion 41 will be deflected increasingly to the left in thedirection of the arrow in Figure as pin 13 rides upwardly along thecontact rib 43.

In the form of my invention shown in Figure 9, full contact pressure isnot reached until final contact has been made as the entire length ofthe contact rib is ramped to provide for spring deflection, hence theprewiping action is bad at a reduced pressure between the elements.

In the embodiment shown in Figure 12 the cleansing power of theprewiping action is enhanced by ramping only the initial portion 45a ofcontact rib 45 whereby once the pin has traversed ramp 45a, as may beseen in the action diagram, Figure 14, full contact pressure will be hadand applied to the greater part of the prewiped length of the pin.

In a simplified form of my invention the contact rib may be formedmerely by turning down the end 49 of contact portion 51 as in Figure 13.Preferably, the end surface of portion 49 is utilized as the contact ribso as to provide a contact path of a width at least equal to the stockthickness. Hence, end 49 is substantially at an angle of 90 with respectto the plane of contact portion 51 and spring portion 53.

In the embodiments of my invention thus far described once the pin haspassed beyond the apex of the V-shaped rib the force required to deflectthe spring decreases since the point of contact is at a greater distancefrom the point at which the spring is anchored. Accordingly, when theplugboard assembly is to be disconnected, the pin retraces its path backalong the contact rib which requires the point of contact to once againmove toward the apex of the V and nearer to the anchoring point of thespring. Thus, until the apex is reached, an increase in force isnecessary to retract the pin along the contact rib whereby to open theplugboard assembly, hence a self-locking action is had. A more positiveself-locking action may be obtained by progressively decreasing theheight of the rewiping portion of the contact rib of the form generallyshown in Figure 9. Thus, in the embodiment shown in Figure 15, prewipingportion 55a of rib 55 progressively increases in height above the planeof contact portion 57 until the apex of the V is reached, whereafter aprogressive but attenuated decrease in height is imparted to rewipingportion 55b. As thus constructed, the force necessary to move pin 13along rib portion 55a gradually increases until the apex is reached,whereupon continued movement of the pin results in a slight relaxationof spring tension clue to both the increase in distance from theanchoring point of the spring to rib portion 55b and the decrease inheight of the rib. In order to disengage the contact assembly there isnow required an increase in deflection of the spring, to the left in theaction diagram, Figure 16, against an increasing resistance of thespring to deflect as the contact point once again approaches theanchoring point.

In Figure 17 a simplified version of the contact rib is shown. In thisform a ramped contact rib 59 extends diagonally across the breadth ofcontact portion 61 and is effective to wipe clean a path along thecontact pin 13, the wiping action being amplified both by the real andthe apparent increase in length of the contact rib.

In the embodiments of my invention thus far described, it will beapparent that the contact member may be formed from sheet metal stock byblanking and forming techniques Well-known in the art, thus lending easeand simplicity of fabrication of the part and by low cost productionmethods.

Figure 18 illustrates a more simplified form wherein contact member 7 isfabricated from wire. In this embodiment two wire legs 63, which may bestaked to the plugboard in any suitable manner, comprise the springportion, the wire ends being joined by a bight portion turned back at anangle of approximately with one leg 65 of the turned back portion beinglonger than the other leg 66 so as to impart the desired ramp to rib 67and to incline the rib with respect to the direction of movement of thecontact pin.

Sufficient contact pressure is, of course, essential to provide a goodeiectrical contact. In the contact assembly of the present invention acontact pressure in the range of 6 to 8 ounces is eiiective for mostapplications. Obviously the degree of contact pressure may be controlledby varying such factors as stock thickness, the type of metal employedand the degree to which the rib is ramped. For those forms of myinvention illustrated in Figures 9 through 18, it is especiallypreferred that relatively thin stock be utilized so as to require a highdeflection to produce the 6 to 8 ounces of pressure. This, in turn,requires a fairly high ramp for the contact rib whereby the target areato be struck by movement of the contact pin is large, lending to a lesscritical arrangement of the contact springs 7 on the face of theplugboard in relation to the mounting of contact pins 13 on the moveableplugboard.

In the specification and accompanying drawings I have shown anddescribed a preferred embodiment of my invention and suggested variousmodifications thereof, but it will be recognized by those skilled in theart that many other modifications may be made without departing from thespirit of the invention. For example, there are many otherconfigurations of the contact rib than those shown which will achieve aprewiping of a path along the contact pin with a subsequent recontactingof the pin within the prewiped path. Accordingly, it is to be understoodthat the embodiments shown, are not intended to be exhaustive norlimiting of the invention but on the contrary are given for purposes ofillustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner ofapplying it in practical use so that they may modify it and adapt it invarious forms, each as may be best suited to the conditions of aparticular use.

I claim:

1. An electrical contact member comprising an elon gated leaf springportion, means at one end of said spring portion for mounting saidmember of a supporting base, and a contact portion at the other end ofsaid spring portion engageable by a mating contact pin adapted to bedisposed substantially parallel. to said member and moved in a planeparallel to the plane of said spring portion, rib means on said contactportion providing a narrow contact surface adapted for slidingengagement with the pin, at least the initial portion of said rib meansbeing inclined to the plane of pin movement to provide a ramp forguiding the pin onto said contact surface and deflecting said springportion, said rib means including a first wiping portion inclined alongthe length of said member for wiping along a predetermined length of thepin and a second terminal portion having an inclination in the oppositedirection from that of said first portion for recontacting the pinwithin the wiped predetermined length.

2. An electrical contact member comprising an elongated leaf springportion, means at one end of said spring portion for mounting saidmember on a supporting base, the other end of said spring portion havingan extension to form a contact portion engageable by a melting contactpin adapted to be disposed substantially parallel to said member andmoved in a plane parallel to the plane of said spring portion, rib-likemeans forming a V on one side and extending substantially the width ofsaid contact portion with the apex of the V approximately at thelongitudinal center of said member, said rib means providing a narrowcontact surface adapted for sliding engagement with the pin, at leastthe initial portion of said rib means being inclined to the plane of pinmovement to provide a ramp for guiding the pin onto said contact surfaceand deflecting said spring portion, at least a portion of said rib meansbeing inclined along the length of said member to effect a wiping alongthe pin upon movement in sliding contact with said surface.

3. An electrical contact member substantially as set forth in claim 2,wherein said contact portion is substantially planar and the legs of theV progressively decrease in height above the plane of said contactportion from the apex of the V.

4. An electrical contact member comprising an elongated leaf springportion, means at one end of said spring portion for mounting saidmember on a supporting base, and a substantially fiat contact portionintegrally extending from the other end of said spring portionengageable by a mating contact pin adapted to be disposed substantiallyparallel to said member and moved in a plane parallel to the plane ofsaid spring portion, the plane of said contact portion being set at anacute angle relative to the plane and about the length of said springportion, rib means on said contact portion providing a narrow contactsurface adapted for sliding engagement with the pin, at least a portionof said rib means being inclined along the length of said member toeffect a wiping along the pin upon movement in sliding contact with saidsurface.

S. An electrical contact member substantially as set forth in claim 4wherein said acute angle is approximately 45.

6. An electrical contact member comprising an elongated leaf springportion, means at one end of said 8 spring portion for mounting saidmember on a supporting base, and a substantially flat contact portion integrally extending from the other end of said spring portion engageableby a mating contact pin adapted to be disposed substantially parallel tosaid member and moved in a plane parallel to the plane of said springportion, the plane of said contact portion being set at an acute anglerelative to the plane and about the length of said spring portion. ribmoans providing a narrow contact surface substantially to a uniformelevation above the plane of and extending substantially across saidcontact portion and adapted for sliding engagement with the pin, atleast a portion of said rib means being inclined along the length ofsaid member to effect a wiping along the pin upon movement in slidingcontact with said surface.

7. An electrical contact member comprising an elongated leaf springportion, means at one end of said spring portion for mounting saidmember on a supporting base, and a substantially flat contact portionintegrally extending from the other end of said spring portionengageable by a mating contact pin adapted to be disposed substantiallyparallel to said member and moved in a plane parallel to the plane ofsaid spring portion, the plane of said contact portion being set at anacute angle relative to the plane and about the length of said springportion, rib means on said contact portion providing a narrow contactsurface adapted for sliding engagement with the pin, said rib meansincluding a first wiping portion inclined along the length of saidmember for wiping along a predetermined length of the pin and a secondterminal portion for recontacting the pin within the wiped predeterminedlength.

8. An electrical contact member comprising a spring portion operativelydeflectable about a bending axis per pendicular to the length thereof,means at one end of said spring portion for mounting said member on asup porting base, and a contact portion at the other end of said springportion having rib-like means defining a relatively narrow raisedcontact path on said member, at least a substantial part of said pathbeing inclined to ward said bending axis and at least the initial partof said path being inclined with respect to both said bending axis andthe direction of deflection of said spring portion, said contact pathbeing substantially V-shaped.

9. A contact system comprising first and second rel atively movablecontact members arranged for sliding engagement under spring pressure,said first member having a cylindrical engaging surface, means formoving said first and second members relatively toward each other alonga line perpendicular to the longitudinal axis of said cylindricalsurface to engage said members, said second member having a generallyfiat face, rib-like means on said face providing a narrow raised contactsurface slidably engageable with said cylindrical surface, said rib-likemeans including a first portion inclined to said axis and said line forwiping said cylindrical surface along its length during initial contactengaging movement of said members, and a second portion angularlydisposed relative to said first portion for engaging said cylindricalsurface at an intermediate point within the wiped length thereof duringfinal contact engaging movement of said members.

10. A contact assembly comprising first and second contact members, saidfirst contact member having a generally cylindrical engaging surface andconstrained for relative movement perpendicular to the longitudinal axisof said cylindrical surface and generally parallel to and across theface of a second contact member under spring pressure, rib-like means onthe face of said' second member providing a narrow raised contactsurface slidably engageable with said cylindrical surface. said rib-likemeans including a first portion inclined to said axis and direction ofmovement of said first contact means for wiping said cylindrical surfacealong its length during contact engaging movement, and a second terminalportion angularly disposed relative to said first portion forrecontacting said cylindrical surface at an intermediate point withinthe wiped portion thereof.

11. An electrical contact member comprising an elongated leaf springportion, means at one end of said spring portion for mounting saidmember on a supporting base, the other end of said spring portion havingan extension to form a contact portion engageable by a mating contactpin disposed substantially parallel to said member and moved in a planeparallel to the plane of said spring portion, rib-like means projectingfrom a face and extending the width of said contact portion to provide anarrow contact surface which is smoothly rounded for sliding and wipingengagement across a length of the pin, said rib-like means having aninitial portion and an intermediate portion and a terminal portion, atleast said initial. portion being inclined to the plane of pin movementto provide a ramp for guiding the pin onto said contact surface anddeflecting said spring portion, at least said intermediate portion beinginclined along the length of said member to effect a wiping along thepin upon movement in sliding contact with said surface,

10 said contact portion being substantially planar with said rib-likemeans progressively increasing in height above the plane of said contactportion all along its entire length across the width of said contactportion.

12. A contact member as set forth in claim 11 wherein the terminalportion of said rib-like means provides a narrow contact surfaceextending along a line at an angle to and intersecting the line of saidintermediate portion.

References Cited in the file of this patent UNITED STATES PATENTS1,213,632 Hammond Jan. 23, 1917 1,359,585 Fitzgerald Nov. 23, 19201,808,555 Ishimaru June 2, 1931 2,120,396 Domaleski June 14, 19382,401,430 Lake June 4, 1946 2,594,748 Earl Apr. 29, 1952 2,738,486Wadsworth Mar. 13, 1956 2,816,275 Hammell Dec. 10, 1957

